Venting roof insulation product

ABSTRACT

A ROOF DECK MATERIAL FOR USE IN AN INSULATED, VENTILATED BUILT-UP ROOFING SYSTEM HAVING A RELATIVELY RIGID BODY OF FOAMED PLASTIC RESIN (E.G. FOAMED POLYSTYRENE) WHICH HAS OPPOSITELY FACING GROOVED SURFACES TO PROVIDE VENTING OR ENTRAPPED MOSITURE WITHIN THE SYSTEM, ESPECIALLY FROM MOISTURE-BEARING CONSTRUCTION MATERIAL (E.G. VERMICULITE CONCRETE) POURED UPON THE DECK MATERIAL DURING INSTALLATION OF THE SYSTEM. THE GROOVES ARE SUFFICIENTLY NARROW TO PREVENT THE UNCURED CONSTRUCTION MATERIAL FROM FILLING THE GROOVES. PREFERABLY, THE GROOVES ARE COVERED WITH A LAYER OF MOISTURE PREMEABLE MATERIAL (E.G. KRAFT PAPER) TO INSURE THE PREVENTION OF FILLING OF THE GROOVES BY THE CONSTRUCTION MATERIAL.

Nov. 16, 1971- R. WLSTERRETT E 3,619,951

I VENTING ROOF INSULATION PRODUCT 1 Filed March 24 1970 FIG. 2 l2 l4 FIG. 3 w

INVENTORS ROBERT W. STERRETT FRANCIS J; JACOB MERLE D. CHAMBERLAIN, DECEASED by LOIS M. CHAMBERLAIN, EXECUTRIX BY WM A 341 ATTORNEY United States Patent Oifice US. Cl. 52-302 7 Claims ABSTRACT OF THE DISCLOSURE A roof deck material for use in an insulated, ventilated built-up roofing system having a relatively rigid body of foamed plastic resin (e.g. foamed polystyrene) which has oppositely facing grooved surfaces to provide venting of entrapped moisture within the system, especially from moisture-bearing construction material (e.g. vermiculite concrete) poured upon the deck material during installation of the system. The grooves are sufficiently narrow to prevent the uncured construction material from filling the grooves. Preferably, the grooves are covered with a layer of moisture permeable material (e.g. kraft paper) to insure the prevention of filling of the grooves by the construction material.

This application is a continuation-in-part of application, Ser. No. 610,524 filed Jan. 20, 1967, now abandoned.

This invention relates to built-up roofs and more particularly to an insulating roof deck material employed in built-up roofing systems, said material having moistureconveying channels.

Lightweight perlite or vermiculite insulating concrete is widely used in roof deck construction. These lightweight aggregate fills are generally a well saturated mix to facilitate easier pouring of the slabs, and the volume of water in the initial mix is considerably in excess of that required for normal concrete hydration. Venting of this free and excess water following the application of bituminous coatings over the insulating slab is important, since it is uneconomical to delay final construction and covering with bituminous materials until after the aggregate has completely cured and dried out.

*Entrapped moisture under the built-up roofing has a tendency to blister the bituminous coating which leads to roof failure. The blisters develop from the vaporization of entrapped moisture by the heat of the sun. Since the atmospheric pressure above the roof is lower than the vapor pressure within the concrete slab the only escape of the vapor is by way of a blister in the coating. The prior art solutions to this problem were not always satisfactory; for example, one method used lightweight concrete grooved slabs to vent the moisture. But these were subject to fracture during storage and transit and leaks developed in the joints between the slabs. Seamless pouring of these slabs in place presented great difliculties for they required molds to form the grooves making the process uneconomical. Grooved wooden boards are not satisfactory because they tend to warp making it difficult if not impossible to apply built up roofing over the uneven surface.

It is therefore an object of the present invention to prevent the build up of entrapped moisture under built-up roofing by providing an improved discharge means for the release of the moisture.

This and other objects of the invention will become apparent from the following detailed description and drawings wherein;

3,619,961 Patented Nov. 16, 1971 FIG. 1 is an isometric view of a foamed polystyrene board of this invention showing moisture conveying grooves;

FIG. 2 is a side view of a grooved foamed polystyrene board of this invention showing the grooved foamed polystyrene board with facing material over the grooves;

FIG. 3 is a side view of a built-up roof employing the grooved foamed polystyrene board of this invention.

Referring now to FIG. 1 there is shown a relatively rigid board 11, which, generally, may have a width of about 2 feet, a length of about 4 to 8 feet and a thickness of about 1 to 4 inches, of foamed polystyrene having oppositely facing plain surfaces. On each surface is a plurality of parallel air space moisture vent grooves 12. Preferably the grooves in one surface are alternately staggered with respect to the grooves in the other surface, as shown in FIG. 1. The board 11 may also be provided with a channel 13 on one or more edges. The channels extend transversely to grooves 12 and are in communication therewith. The grooves 12 should be narrow enough that they will not normally fill with covering material (such as lightweight concrete) and at such a depth sufficient to effectively convey moisture vapors from the covering material. In a particularly preferred embodiment of the invention, grooves 12 are about inch wide and about inch deep.

The board of this invention can also be prepared with a facing material covering the grooves 12. FIG. 2 shows a facing material 14 which is used to prevent filling of the grooves 12 by covering material. Suitable facing materials should be porous, that is permeable to moisture vapors and among the materials which can be used are glass fiber screen, woven plastic materials, permeable plastics and papers, for example, kraft paper.

FIG. 3 shows a built-up roof constructed using the polystyrene board of FIG. 2. Here, the polystyrene board 11 having permeable facing material 14 covering grooves 12 is situated upon a base member 15, for example, concrete. Lightweight insulating concrete such as vermiculite concrete, is poured over board 11 to form insulation layer 16. A layer 17 of water-impermeable material e.g., bituminous-coated roofing felt, forms the surface of the builtup roof. The grooved polystyrene board acts as a venting member allowing the escape of entrapped moisture via grooves 12 and 13. Base member 15 is illustrated as concrete but it may also 'be constructed of wood, metal, etc. It is within the scope of the present invention to use other relatively rigid foamed plastic materials such as foamed polyurethane for the board. The invention has been described using polystyrene as the preferred material.

We claim: 1. A method of constructing ventilated insulated builtup roofing over a structural base member comprising:

(a) overlaying said base member with an intermediate venting member comprising a relatively rigid body of foamed plastic resin having oppositely facing plain surfaces each provided with a plurality of parallel air space moisture vent grooves; (b) pouring a layer of moisture bearing construction material over said venting member; (0) curing said moisture bearing construction material; and (d) placing a layer of water-impermeable material over said layer of construction material; said air space moisture vent grooves having a width sufficiently narrow that said moisture bearing construction material will not fill said grooves, whereby said grooves act to ventilate entrapped moisture at the interfaces between said base member, said venting member and said construction material, respectively.

2. The method of claim 1 wherein the oppositely facing surface of said intermediate venting member upon which 3 said moisture bearing construction material is poured and grooves therein are covered with a layer of permeable material prior to said pouring of moisture bearing construction material to prevent said material from entering said grooves.

3. The method of claim 2 wherein said foamed plastic resin is polystyrene.

4. The method of claim 3 wherein said permeable layer is kraft paper.

5. An insulated ventilated built-up roof comprising:

(a) a structural base member of a material selected from the group consisting of concrete, wood and metal;

(b) an intermediate venting member positioned upon said base member comprising a relatively rigid body of foamed plastic resin having oppositely facing upper and lower surfaces each having a plurality of parallel air space moisture vent grooves therein; said upper grooved surface being covered with a layer of kraft paper; and

(c) a layer of cured vermiculite or perlite lightweight concrete positioned above said permeable material;

and

(d) a surface layer of bituminous material disposed above said cured concrete.

6. The built-up roof of claim 5 wherein said venting member has parallel side surfaces normal to said upper and lower surfaces, said side surfaces having transverse channels formed therein at right angles to said grooves, said channels being positioned between said surfaces so as to communicate with each of said grooves.

7. The built-up roof of claim 6 wherein said resin is polystyrene.

References Cited UNITED STATES PATENTS 3,455,076 7/1969 Clarvoe 52302 3,498,015 3/1970 Seaburg 52-302 FOREIGN PATENTS 961,133 1964 Great Britain 52-402 712,301 1965 Canada 5'2-302 JOHN E. MURTAGH, Primary Examiner US. Cl. X.R. 52-309, 746 l 

